Question

How would you balance the following equation: I2+HNO3-->HIO3+NO2+H2O?

Answer 1

This is a redox reaction, which may be approached by oxidation and reduction half equations.

Explanation:

Oxidation:
Elemental iodine is oxidized to `IO_3^-`, iodate.

`1/2I_2 +3H_2O rarr IO_3^(-) +5e^(-) + 6H^+` `(i)`

Reduction:

Nitric acid is reduced to nitric oxide `N^(V)rarrN^(IV)`:

`HNO_3 +H^+ +e^(-)rarr NO_2 +H_2O` `(ii)`

The overall redox reaction is `(i) + 5xx(ii)` `=` the overall redox equation:

`1/2I_2 + 5HNO_3 rarr IO_3^(-) +5NO_2 + 2H_2O +H^+`

Alternatively, I could write:

`1/2I_2 + 5HNO_3 rarr HIO_3 +5NO_2 + 2H_2O`

Are the final equations balanced with respect to mass and to charge? Don't trust my arithmetic. How would I remove the half coefficient on `I_2`?